People, pigs and infant formula

Date posted: February 24, 2012

Dr. Jack Odle's work with baby pigs suggests that a food additive called polydextrose may be an important addition to human infant formulas. Pictured from left are Dr. Lin Xi, research assistant professor in animal science; Brynn Seabolt, research associate; and Odle.

Infant formulas may be more like human breast milk and provide more of the qualities that make breast milk such an important part of an infant’s development if the formula contains a soluble fiber source called polydextrose.

That is the conclusion of a North Carolina State University study using baby pigs that were fed a modified infant formula that contained polydextrose, a glucose polymer that is used as a soluble fiber source in some foods.

Polydextrose appears to be a good substitute for oligosaccharides that are found in breast milk, said Dr. Jack Odle, William Neal Reynolds professor of nutritional biochemistry. Odle is an animal scientist whose work focuses on understanding the nutritional requirements of young, developing animals, particularly pigs. But pigs, Odle points out, are good substitutes for people.

“I’m an animal scientist first, so I’m interested in the pig for the sake of the pig,” Odle said. “But they (pigs) really are an excellent model for pediatric nutrition.”

In the study, piglets fed a formula that contained various amounts of polydextrose were compared to piglets nursed by their mother and piglets fed formula without polydextrose. Odle was particularly interested in the effect polydextrose may have on the development of the gastrointestinal system and immune function.

The study was funded and done in collaboration with Mead Johnson Nutrition, a maker of infant formula and other nutritional products for infants and children. A paper describing the study appeared in 2011 in The Journal of Nutrition.

“When you look at this stage of life — the newborn — one of the areas where they’re most challenged is in their gastrointestinal health,” Odle explained. “When they’re born, the GI tract is sterile, so in early life the ecosystem of the gut has to develop from scratch. Inputs (what the infant eats) really have quite a large influence on that. They’re starting from zero.”

Odle is quick to acknowledge that human breast milk is the gold standard where human nutrition is concerned. But breast milk isn’t always available, and newborns must sometimes be fed formula.

Odle said infant formula makers have made strides toward approximating the nutritional value of breast milk with one exception, the presence of oligosaccharides. Oligosaccharides are indigestible carbohydrates that appear to play an important role in the development of the immune system and a healthy gastrointestinal tract. While oligosaccharides make up a large percentage of breast milk, they exist in many different forms, so it’s difficult to come up with an oligosaccharide substitute, Odle said.

Oligosaccharides are known as prebiotics, food ingredients that promote the development of bacteria in the GI tract that aid health. Oligosaccharides promote the development in the gastrointestinal tract of bacteria such as lactobacilli that aid gastrointestinal health.

When Odle compared the intestinal tracts of sow-reared pigs with pigs fed a modified infant formula that included different amounts of polydextrose, he found that more polydextrose in the formula meant more lactobacilli in the gastrointestinal tract. In addition, gastrointestinal concentrations of propionic and lactic acid increased with increased amounts of polydextrose. Increased amounts of propionic and lactic acid are indications of good gastrointestinal health.

“We’re finding that if you change this (gastrointestinal) microbial population, it communicates with the intestinal immune system and can influence the immune status, certainly, of the intestine, and perhaps even systemically of the rest of the body in a favorable way,” Odle said.

Odle said polydextrose is already included in some infant formulas. This study indicates that the presence of polydextrose in the list of ingredients that make up an infant formula may mean that the formula will be more likely to promote gastrointestinal health and a robust immune system.

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